低埋深比插入式柱脚抗震性能试验

Experiment on seismic behavior of embedded column base with low embedment ratio

摘要:

为研究低埋深比插入式柱脚的抗震性能,设计了8个缩尺比例为1∶2的柱脚节点,试验中以是否布置栓钉、埋深比、轴向荷载以及翼缘厚度为变化参数,对柱脚的破坏模式、滞回曲线、骨架曲线、延性、刚度退化以及耗能能力展开分析。结果表明:低埋深比插入式柱脚有两种破坏模式,分别是混凝土二次浇筑面破坏和型钢柱底部屈曲破坏；布置栓钉或施加轴向压力可有效改善插入式柱脚的破坏模式,由二次浇筑面破坏转变为底部型钢屈曲破坏,提高柱脚的耗能能力；无栓钉且无轴向压力作用下,埋深比由1.0提高至1.5,能够减轻二次浇筑面的破坏程度并保证其继续承载,但不能改变破坏模式；工程应用中插入式柱脚在埋深比1.0时应布置栓钉。

Abstract:

To study the seismic performance of embedded column base with low embedment ratio, eight column bases with a scale ratio of 1∶2 were designed to carry out experiments. The effects of parameters such as stud, embedment ratio, axial load, and flange thickness on the failure mode, hysteretic curve, skeleton curve, ductility, stiffness degradation, and energy dissipation capacity of the column bases were analyzed. Results show that the embedded column base with low embedment ratio had two failure modes, i.e., the secondary pouring surface failure of the concrete and the buckling failure of the bottom of the steel column. The failure modes of the embedded column base could be effectively improved by arranging studs or applying axial pressure, which could transform the secondary pouring surface failure into the buckling failure of the steel bottom and improve the energy dissipation capacity of the column base. When the embedded column base was under no stud and no axial load, the increase of the embedment ratio from 1.0 to 1.5 reduced the damage degree of the secondary pouring surface and ensured its continued bearing capacity, but could not change the failure mode. In engineering design, studs should be set when the embedment ratio of the embedded column base is equal to 1.0.